840221 has 4 divisors (see below), whose sum is σ = 846492. Its totient is φ = 833952.

The previous prime is 840197. The next prime is 840223. The reversal of 840221 is 122048.

840221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 688900 + 151321 = 830^2 + 389^2 .

It is a cyclic number.

It is not a de Polignac number, because 840221 - 2¹⁸ = 578077 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 840221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (840223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2930 + ... + 3203.

It is an arithmetic number, because the mean of its divisors is an integer number (211623).

2⁸⁴⁰²²¹ is an apocalyptic number.

It is an amenable number.

840221 is a deficient number, since it is larger than the sum of its proper divisors (6271).

840221 is a wasteful number, since it uses less digits than its factorization.

840221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6270.

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 840221 is about 916.6356964465. The cubic root of 840221 is about 94.3621535662.

Adding to 840221 its reverse (122048), we get a palindrome (962269).

The spelling of 840221 in words is "eight hundred forty thousand, two hundred twenty-one".